Flow device



p 1963 c. R. BROMAN 3,103,928

FLOW DEVICE Filed Nov. 14, 1960 1m! @rus Kflrcrmr-c J m, wwwv gg m My @J United States Patent Ofiice 3,103,928 Patented Sept. 17, 1963 3,103,923 FLUW DEVICE Cyrus R. Broznan, 3205 Otto Lane, Evanston, Ill. Filed Nov. 14, 1960, Ser. No. 68,840 It) Ciairns. (Cl. 128-214) This invention relates to a flow device. A particular application of the device is in the field of surgery employing hypothermia.

In hypothermia, the patient is literally chilled so as to produce a blood temperature of the order of 4 C. (approximately 40 F.). This technique has become increasingly employed, particularly in heart surgery. A desirable adjunct to heart surgery is the employment of an artificial ox genator and pump, so that the heart can be quieted. Artificial oxygenation of blood is desirably achieved at ordinary room temperatures, i.e., about 75 F. The flow device of the instant invention can be used advantageously to first raise the blood temperature in the extra-corporeal circuit, and subsequently reduce it after the blood has been oxygenated The provision of such a device thus constitutes an objective of this invention.

Heretofore, the heat exchange type devices employed in conjunction with hypothermia were characterized by a number of drawbacks. In some instances, the devices functioned imperfectly, creating clots, entrapping oxygen, etc., so that the very success of the operation was threatened by the use of these adjunctive devices. The overcoming of these problems and drawbacks constitutes another objective of this invention. I

Still another object of the invention *is to provide a novel flow device which is operative in transfer phe nomena, as in a heat exchanger of the character just described. Yet another object is to provide a disposable type of transfer unit which is characterized by unique structural features whereby a highly efiicierrt operation may be developed.

A further object of the invention is to provide a novel heat exchanger apparatus in which a flexible unit is mounted within a rigid open frame to provide increased efliciency of operation while simultaneously affording safeguards against mis-operation.

Other objects and advantages of the invention may be seen in the details of construction and operation set forth in this specification.

The invention will be explained in conjunction with an illustrative embodiment in the accompanying drawing, in which- FIG. 1 is an elevational view, of generally schematic form, showing an application of the invention to a surgical operation;

FIG. 2 is an elevational view of the inventive apparatus (seen in smaller and less detailed form in FIG. 1);

FIG. 3 is a fragmentary elevatiorral view, partially in section, of the transfer unit seen in smaller size in the preceding views; and

FIG. 4 is a sectional view of the transfer unit such as would be seen along the sight line 4-4 of FIG. 3.

In the illustration given, and with particular reference to FIG. 1, the numeral designates generally a surgical patient seen in a reclining position. Attached to the patient 10 are conduit lines 11 and 12. For the sake of illustration, the conduits 11 and 12 are connected as they would be in heart surgery, wherein the heart is quieted. The conduit 11 conducts venous blood from the vena cava (not shown) and delivers blood to the extra-corporeal circuit generally designated 13. The conduit 12 returns the arterialblood from the circuit 13, usually to the main aortic artery.

The extra-corporeal circuit 13 of the illustration given includes two heat exchange devices generally designated 14 and an oxygenating device 15 which may also include the usual circulating pump (not shown). One device 14 is employed for raising the blood temperature from 40 F. to F., this particular unit being designated 14a and being in the path of flow of venous blood. The other apparatus 14b reduces the temperaturefrom 75 F. to 40 F. and handles arterial blood, being between the entra-corporea-l device 15 and the delivery conduit 12.

It will be appreciated that a variety of forms of extracorporeal devices and pumps 15 may be employed in conjunction with the illustrated arrangement, and, be cause of this, the device 15 has merely been represented by a block. Contemporary artificial oxygenators partake of a variety of forms, and, for that matter, the device 15 may advantageously in some instances be something other than an artificial *oxygenator, such as an artificial kidney.

Each apparatus 14 is seen to include anouter enclosure 16. This may take the form of a tank having a liquid inlet 17 and a liquid outlet 18. A heating medium is circulated through the tank 16 employed with the device 14a, while a coolant is introduced into the inlet 17 of the apparatus 14b.

Mounted within the container or tank 16 is a.transfer unit generally designated 19 and which is seen in FIG. 2 to include a rectangular rigid frame generally designated 20 having a rectangular opening 21 therein. In the illustration given, the frame 20 is provided by vertically-extending rods 22 and 23 which are connected at the top and bottom by cross members 24 and 25, respectively. Each member 24 and 25 is equipped with a turnbuckle 26 which perm-its adjustment of the spacing of the rods 22 and 23. The ends of the cross members 24 and 25 are rigidly coupled or integrated'to the rods 22 and 23 so that an overall rigid framework is provided. Connected to the upper ends of the frame 20 are arms 27 and 2-8. At their upper ends, arms 27 and 28 are eccentrically and pivotally coupled to a rotatably-mounted element 29. In effect, acarn action is developed which moves the frame 20 in a planar fashion as the element 29 is rotated.

Mounted within the central rectangular opening 21, more specifically on the side rods 22 and 23, is a transfer element generally designated 30 and which can be seen in greater detail in FIGS. 3 and 4.

Referring now to FIG. 4, it will be seen that the element 30 is constructed of two sheets of material 31 and 32. The upper sheet 31 is the only sheet shown and designated in FIG. 3. Both sheets, however, are of the same size and are arranged in superposed, aligned relation, each sheet being generally rectangular in outline, as can be appreciated from FIG. 3. The rectangular outline is defined by opposite longitudinal side edges 33 and 34 and by transverse side edges 35 and 36. The sheets 31 and 32 optimally may be constructed of polyvinyl chloride of a thickness of the order of IMO-.0 18 inch. Such material is transparent and flexible and may be obtained from the Ellay Rubber Company, of Los Angeles, California. Such material has received the approval of the Department of Health, Education and Welfare of the United States Government for use in construction of plastic containers for the collection, storage and dispensing of human blood. This material is also readily heat-sealed, and this procedure constitutes the preferred mode of uniting or joining the two sheets together.

For example, the sheets 31 and 32 are heat-sealed along lines 37 and 38 which abut the side edges 33 and 34, respectively. Additionally, the sheets are united along parallel lines 39 and 40, which are adjacent to but spaced from the lines 37 and 38. Thus, the unions along the lines 37 and 39 develop a pocket 41 (see FIG.

4) which is adapted to receive one of the rods 22 or 23. The other rod 23 or 22, as the case may be, is receivable in the pocket 42 developed between the unions along the lines 38 and 40.

The sheets 31 and 32 are further united along a plu rality of generally transverse lines, which lines are generally designated by the numeral 43 in FIG. 3. The lines of union 43 include lines 43a to 43 which are those of the lines intersected by the sight line 44 in FIG. 3. The counterpart structure is given the same designation in FIG. 4 by means of the symbols 43a, 4312, etc. Each of these lines is substantially identical in length, and it will be appreciated from a consideration of FIG. 3 that the lines terminate spaced distances from the lines 39 and 40, the lines 43a, etc. lying between the lines 39 and 40.

The outermost lines 433 and 43 of the plurality of lines 43 difier from the remaining intermediate lines in that one end of each line 43g and 431 is extended as at 431' relative to line 43g and at 430 relative to line 43 to couple the respective lines to the lines of union 39 and 40, respectively.

Immediately adjacent line 39 in the upper lefthand corner of the structure seen in FIG. 3, is provided an inlet fiow fitting 44. This may take the form of a A" 1D. vinyl tube which has been immobilized between the sheets 31 and 32 by spot heat-seals as at 44a. It will be seen that the lower spot heat-seal 44a abuts the end of line 43f opposite the short connection line 430.

The envelope shown in dotted line in FIG. 3 and designated generally by the numeral 45 is defined by the upper ends of the plurality of lines 43. This envelope 45, together with the short line union 431' and the longer line union 39, defines an inlet passage 46 for a medium to be subjected to a transfer operation. For example, when the unit is installed as at 14a in FIG. 1, venous blood at a temperature of about F. is introduced into the inlet fitting 44. The blood entering the inlet fitting 44 is confronted by a plurality of alternative flow paths leading from the inlet passage 46. These paths are provided by the coaction of the various linesmaking up the plurality of line unions 43.

In like fashion, an outlet passage 47 is provided which is defined by the envelope generally designated 48 based on the lower ends of the lines 43, the short stub line union 430, and a portion of the linear heat-seal 40. An exit port as at 49 is provided in the lower righthand corner of the structure seen in FIG. 3, and this would deliver 75 F. blood if the unit 30 were installed as at 14:: in FIG. 1.

Still referring to FIG. 3, it will be seen that the envelope-defining lines and 48 are arranged at an angle to the lines 39 and 40 so as to provide tapering inlet and outlet passages 46 and 47, respectively. The lines 43 are equally spaced apart and are disposed parallel to each other so that a plurality of substantially identical intermediate flow passages 50 are provided between the inlet passage 46 and the outlet passage 47. For that matter, the flow path from the inlet 44 to the outlet 49 is of the same length irrespective of which intermediate passage 50 is followed. The lines 43 are seen to be inclined relative to the line 39, and at an obtuse angle on the side thereof adjacent the inlet fitting 44.

In operation, two units 30 may be employed in the stations designated 14a and 14b in FIG. 1, where they will carry out heating and cooling operations, respectively. I have found that the structure provided is characterized by an advantageous uniform distribution of resistance in that the various alternative flow paths are of the same length and the same transfer surface area. This is particularly important in the case of handling blood close to its freezing'temperature, since unequal resistance in one flow path may cause the blood to freeze and hemolyze.

It will be appreciated that the medium circulated in be lower than 40 F. in order to assure proper cooling of the blood. If the flow in one alternative path is too sluggish and the residence time of a given moiety of blood is too long, then the blood may become frozen and effectively block off that particular path. This necessarily impairs the efiiciency of the unit and, more critically, should the frozen blood subsequently again become fluid, there would be administered imperfect or hemolyzed blood, with the consequent potential danger to the patient. Thus, the provision of uniform resistance, irrespective of the flow path, is not only desirable but mandatory.

I have also found that the efficiency of the transfer device can be materially enhanced through the provision of the agitating motion developed by the rotating element 29. This functions to move the frame 20, hence the unit 30, in a generally planar fashion and thus lowers the film transfer coefficients existing between the blood and the heating or cooling medium, as the case may be. In some instances, the structure described may be utilized as a mass transfer medium, as where the unit 30 is mounted within a confined chamber of oxygen in an artificial oxygenator or in a chamber of circulating saline for dialysis, as would be the case in an artificial kidney. In any event, the reciprocatory movement afforded by movement of the frame 20 is advantageous in reducing film coefficients. Further, the frame stabilizes the unit 30 in a planar fashion so as to minimize any tendency of folding or creasing thereof which might introduce a variable resistance in different flow paths. The turnbuckles 26 permit tensioning of the unit 30 to further minimize any tendency to fold.

In the illustration given, I have found that advantageous uniformization of flow through the various fiow paths 50 develops through the use of the tapered inlet and outlet passages 46 and 47, respectively. Each passage, at its larger end, has a transverse dimension of a size such that no resistance is placed on the blood entering therein. For example, the dimension X seen in the upper left-hand corner of FIG. 3, when the unit 30 is fiat and undilated, is one-half the internal circumference of the fiow fitting 44.

The employment of a transparent plastic material is also advantageous in that it permits ready visual determination of the presence of any occluded air, oxygen, carbon dioxide, etc., which might also upset the desirable uniform pressure of the various flow paths. Further, in this connection, the agitation afforded by having rotatablymounted element 29 serves to quickly dislodge any entrapped air bubbles so that, at the very worst, any pressure differential is temporary. Still further, the uniform resistance, irrespective of flow path, exists over a wide range of flow rates. Depending upon the usage and the patient, flow rates as low as cc. per minute up to several hundred cc. per minute may be employed. Throughout this entire range, the flow distribution is uniform.

After a given transfer is concluded, the unit 30 can be readily removed from the housing 16, as by grasping the arms 27 and 28. The conduits 1-1 and 12 may be clamped and out or detached from the unit 30 as through the use of suitable connector fittings (Luer adapters, etc.) 30a, and the unit thereafter discarded.

While, in the foregoing specification, I have set forth a detailed description of an embodiment of the invention for the purpose of illustration thereof, many variations in the details herein given may be made by those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extracorporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygenator alsoconnected in said conduit between said heat exchangers, and means for contacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a rigid open frame, a transfer member tensionally secured within said frame, said member comprising a pair of flexible plastic sheets united together along spaced apart lines to define an entrance passage and an exit passage, and a plurality of substantially identical passages interconnecting said entrance'and exit passages.

2. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extra-corporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygenator also connected in said conduit between said heat exchangers, and means for contacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a rigid frame equipped with a generally rectangular opening, a generally rectangular, flat, flexible element in said opening and secured to said frame to prevent said element from being folded on itself, and a plurality of substantially identical passages in said element each connected to an inlet and outlet in said element.

3. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extra-corporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygenator also connected in said conduit between said heat exchangers, and means for contacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a rigid frame equipped with a generally rectangular opening, a generally rectangular flat flexible element secured in generally planar relation in said opening, said element comprising sheets of thermoplastic resinous material arranged in face-to-face contacting relation and united along a plurality of lines to define a plurality of flow passages, and an inlet and an outlet in said element, each of said passages having substantially the same transfer area.

4. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extra-corporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygenator also connected in said conduit between said heat exchangers, and means for contacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a rigid open frame, a transfer member tensionally secured within said frame, said member comprising a pair of flexible plastic sheets united together along spacedapart lines to define an entrance passage and an exit passage, a plurality of substantially identical passages interconnecting said entrance and exit passages, an outer container for said frame, a fluid medium in said outer container, and means for introducing a liquid medium into said entrance passage.

5. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extra-corporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygenator also connected in said conduit between said heat exchangers, and means for contacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a rigid frame equipped with a generally rectangular opening, a generally rectangular flat flexible element secured in generally planar relation in said opening, said element comprising sheets of thermoplastic resinous material arranged in face-to-face contacting relation and united along a plurality of lines to define a plurality of flow passages, an inlet and an outlet in said element, each of said passages having substantially the same transfer area, a fluid-containing outer container for said frame, and means for agitating said frame parallel to the plane of said element.

6. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extra-corporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygen ator also connected in said conduit between said heat exchangers, and means forcontacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a pair of flexible flat sheets arranged in face-toface, aligned relation, said sheets being interconnected along opposite sides by a plurality of lines defining an inlet passage and an outlet passage spaced therefrom and generally parallel therewith, said sheets being further interconnected along a plurality of generally parallel lines extending between said inlet and outlet passages and defining a plurality of flow channels to provide a plurality of alternate, generally equally-surfaced paths for fluid entering said inlet passage and exiting from said outlet passage.

7. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extra-corporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygenator also connected in said conduit between said heat exchangers, and means for contacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a pair of flexible, generally transparent, flat sheets arranged in face-to-face, aligned relation, said sheets being interconnected along a plurality of lines defining an inlet passage and an outlet passage spaced therefrom and generally parallel therewith, said sheets being further interconnected along a plurality of generally parallel lines extending between said inlet and outlet passages and defining a plurality of flow channels.

8. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extra-corporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygenator also connected in said conduit between said heat exchangers, and means for contacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a pair of flexible flat sheets arranged in face-toface aligned relation, said sheets being interconnected along opposite sides by a plurality of lines defining an inlet passage and an outlet passage spaced therefrom and generally parallel therewith, said sheets being further interconnected along a plurality of generally parallel lines extending between said inlet and out-let passages and defining a plurality of flow channels, and means between each passage and the edge defining the side adjacent each passage for maintaining the connected sheets in a substantially planar condition.

9. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extra-corporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygenator also connected in said conduit between said heat exchangers, and means for contacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a pair of generally transparent, rectangular sheets constructed of lay-flat thermoplastic material and arranged in superposed aligned relation, said sheets bein'g fusedly interconnected along lines adjacent and generally parallel to opposite sides of the superposed assembly, said sheets being additionally interconnected along a plurality of parallel lines extending at an angle to the firstnnentioned lines, said plurality of lines lying between said first-mentioned lines and terminating a spaced distance therefrom to define a plurality of alternative, generally equally surfaced flow paths.

10. In apparatus for practicing hypothermia, a conduit adapted to be connected at the ends thereof to a patient for extra-corporeal circulation of blood, a pair of heat exchangers interconnected in said conduit, an oxygenator also connected in said conduit between said heatexchangers, and means for contacting each exchanger with a heat transfer liquid, each of said heat exchangers comprising a pair of generally transparent, rectangular sheets constructed of lay-flat thermoplastic material and arranged in superposed aligned relation, said sheets being fusedly interconnected along lines adjacent and generally parallel to opposite sides of the superposed assembly, said sheets being additionally interconnected along a plurality of parallel lines extending at an angle to the firstmentioned lines, said plurality of lines lying between said first-mentioned lines and terminating a spaced distance therefrom, the space between one of said firstmentioned lines, and one set of ends of said plurality of lines defining an inlet passage and the space between the other of said first-mentioned lines and the other set of ends of said plurality of lines defining an outlet passage, an inlet port communicating at one end of the inlet passageproviding space and an outlet port communicating with one end of the outlet passage-providing space, said ports being positioned on opposite sides of said assemblies, the

other ends of said inlet and outlet passages being closed.

References Cited in the file of this patent UNITED STATES PATENTS 2,845,929 Strurnia Aug. 5, 1958 2,876,769 Cordova fi Mar. 10, 1959 2,981,253 De Wall et al Apr. 25, 1961 3,064,649 Fuson Nov. 20, 1962 FOREIGN PATENTS 219,006 Australia Nov. 27, 1958 1,208,374 France Sept. 14, 1959 Denmark June 15, 1959 

1. IN APPARATUS FOR PRACTICING HYPOTHERMIA, A CONDUIT ADAPTED TO BE CONNECTED AT THE ENDS THEREOF TO A PATIENT FOR EXTRA-CORPOREAL CIRCULATION OF BLOOD, A PAIR OF HEAT EXCHANGERS INTERCONNECTED IN SAID CONDUIT, AN OXYGENATOR ALSO CONNECTED IN SAID CONDUIT BETWEEN SAID HEAT EXCHANGERS, AND MEANS FOR CONTACTING EACH EXCHANGER WITH A HEAT TRANSFER LIQUID, EACH OF SAID HEAT EXCHANGERS COMPRISING A RIGID OPEN FRAME, A TRANSFER MEMBER TENSIONALLY SECURED WITHIN SAID FRAME, SAID MEMBER COMPRISING A PAIR OF FLEXIBLE PLASTIC SHEETS UNITED TOGETHER ALONG SPACED APART LINES TO DEFINE AN ENTRANCE PASSAGE AND AN EXIT PASSAGE, AND A PLURALITY OF SUBSTANTIALLY IDENTICAL PASSAGES INTERCONNECTING SAID ENTRANCE AND EXIT PASSAGES. 